The invention relates to a coolant pump arrangement for an internal-combustion engine of a motor vehicle including engine shafts. The coolant pump arrangement includes a pump housing and a pump shaft, one end of which is provided with a pump impeller.
Conventionally, the required cooling of motor vehicle internal-combustion engines takes place by use of a coolant, such as water, which circulates in a coolant circulation system and absorbs heat in areas to be cooled and releases this heat again at a different point by way of heat exchangers. Pumps are provided for circulating the coolant.
German Patent document DE 199 41 891 A1, for example, describes a water pump arrangement of this type. Accordingly, the water pump has a pump housing, which is formed of a pump body and a pump covering, and which is connected with the crank case of the internal-combustion engine. The pump shaft is accommodated in the pump housing and is rotatably disposed in a shaft supporting section. The shaft supporting section has a length corresponding to three times the pump shaft diameter and is acted upon by oil for lubrication. The lubricating oil is fed from the crankcase by way of an oil feeding opening. For sealing off the pump space, a sealing device is provided, which axially adjoins the shaft supporting section.
Because of the pump shaft bearing and, in addition, as a result of the sealing device axially adjoining the latter, this water pump arrangement has a very long dimension, which may be disadvantageous, depending on the installation position, particularly when the internal-combustion engine is used in a motorcycle. Also, long coolant hoses are required for connecting the water pump.
An internal-combustion engine having an engine shaft, which is to accommodate as many components as possible relevant to the operation of the engine, is shown and described in German Patent document DE 199 45 948 A1. In addition to mass balance weights, this engine shaft accommodates an impeller on an end side for circulating coolant, the water pump housing being integrated as a function of the arrangement of the engine shaft in the crankcase or in the cylinder head.
Such an integration of the water pump arrangement in the crankcase or the cylinder head requires a high expenditure construction, for example, with a T-joint on the cylinder head, a special seal and/or additional bearings. Also, a special machining of the cylinder head is required, and the pump arrangement cannot be uncoupled.
It is, therefore, an object of the invention to further develop a cooling pump arrangement of the above-mentioned type with a view to a compact, short internal-combustion engine, particularly for a use in a motorcycle, while simultaneously providing a simple and maintenance-friendly construction.
This object is achieved by a coolant pump arrangement for an internal-combustion engine of a motor vehicle including engine shafts, having a pump housing and a pump shaft with a pump impeller arranged on one end, wherein an essentially cantilevered bearing of the pump shaft is provided by a bearing arranged inside the internal-combustion engine. The basic idea is the essentially cantilevered bearing of the pump shaft by way of a bearing arranged within the internal-combustion engine. According to the invention, the bearing is arranged inside the internal-combustion engine in the cylinder head or in the crankcase.
Particularly preferred embodiments and further developments of the invention are described and claimed herein.
According to a particularly advantageous embodiment of the invention, the pump shaft is non-rotatably and coaxially connected with an engine shaft driving it, particularly with a camshaft. The rotational water pump speed and, thus also the pumping capacity, are therefore directly dependent on the rotational speed of the internal-combustion engine. According to another embodiment, the pump shaft is drivable indirectly or directly by another engine shaft.
The bearing of the pump shaft expediently takes place by way of the last engine shaft bearing arranged adjacent to the pump arrangement. If the pump shaft is connected with a camshaft, the last camshaft bearing is simultaneously the bearing element for the pump shaft carrying the pump impeller.
In a preferred embodiment of the invention, a sealing device, particularly a slide ring seal, is arranged between the pump housing and the pump shaft, by which slide ring seal, a centering takes place simultaneously. The slide ring seal is further developed in the manner of a tube section and, by way of its radially interior surface seals off against the pump shaft. By way of its radially exterior surface the sealing device is supported on the inside radius of a receiving device on the pump housing, on the one side, and in a centering manner on the inside radius of a receiving device on the crankcase, on the other side.
It is considered to be very expedient for fixing the pump impeller and the pump shaft on the engine shaft by way of a screwed connection to construct the pump shaft to be hollow and the engine shaft to have a thread on an end side. In this case, the pump shaft is centered on the inside and the outside on the engine shaft.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.